The present invention relates to a burnishing machine and particularly to a mounting system for quickly disconnecting the pad driver from the motor drive to allow replacement of a burnishing pad.
Commercial burnishers operate at a relatively high speed, as, for example, from 2000 to 2500 rpm. At such high speeds as compared to floor scrubbers which may operate at from 200 to 400 rpm, the burnishing pad must be nearly perfectly centered for balancing to prevent unnecessary vibration and shaking during operation, which could cause excessive wear on the machinery itself as well as make it difficult for the operator to properly utilize the machine. Prior art burnishing machines, such as commercially available Model No. BR-2250/2500 available from the Tennant Company or Model No. 608525 also available from the Tennant Company, provide a burnishing driver which is fixedly mounted to the drive shaft of the motor drive with a threaded fastener, such that in order to replace a burnishing pad it is necessary to tilt the machine to raise the burnishing driver away from the floor surface, reach underneath, remove the used pad, and manually center a new pad in position on the pad driver. Frequently, installation of the pad from the bottom of the machine upwardly is difficult inasmuch as the pad driver has hooks which attach to the pad, making it difficult for an operator to reposition the pad if not properly centered on the first attempt. The Velcro-like hooks prevent shifting of the pad once attached to the pad driver.
One solution to this problem has been to provide a pad driver with an outwardly downwardly flared skirt which only allows the pad to be positioned on the driver within the periphery of the skirt. Such as system, however, presents a downwardly projecting circular edge which, if the burnishing machine is tilted during operation, can gouge and mar the floor being polished utilizing the machine. It also adds cost to the machine.
Some attempts have been made to provide a burnishing machine with a motor housing which tilts upwardly and outwardly from the body of the burnishing machine to provide improved access for the removal and replacement of a burnishing pad. Such construction, however, adds greatly to the cost of the machine and its complexity and, therefore, its tendency to fail during its lifetime. This system is also undesirable because it tends to increase the length of the machine since the motor tipping action prevents components from being located above it.
Although quick disconnect systems have been employed for low speed scrubbing machines, such as represented by U.S. Pat. No. 4,866,804 which provides a scrubbing pad holder which is held in place utilizing a snap-on O-ring coupling, such a coupling is inoperable at speeds in excess of about 1500 rpm and particularly in the range of 2000 to 2500 rpm encountered with high speed burnishing machines. Other low speed scrubbing machines have employed twist-on bayonet-type quick disconnects and spring-loaded, snap-on quick disconnects for removing the scrubber driving disk and associated scrubbing pad from the machines. Again, although suitable for low speed scrubbing devices, they are not sufficiently secure to operate at the high speeds encountered in burnishing machines.
Accordingly, there exists a need for an improved system by which burnishing pads can be relatively easily removed and reinstalled in a centered fashion on a burnishing machine utilizing a reliable, relatively low cost coupling system which is capable of withstanding the high speed operation encountered in the burnishing field.
The system of the present invention solves the existent problem by providing a quick disconnect hub which is fixedly secured to the motor drive shaft and which receives a spin-off high pitch threaded pad driver disk to which a burnishing pad is mounted. A spring-loaded locking pin is provided between the burnishing motor housing and selectively locks the drive hub against rotation when it is desired to remove the driver disk by rotating two or three times, thus allowing the removal of the pad driver from the motor and allowing the centered mounting of a burnishing pad to the driver remote from the machine. In a preferred embodiment of the invention, the hub and disk are threaded in a direction such that rotation of the hub by the drive motor tends to tighten the disk onto the hub during operation of the burnishe. In a preferred embodiment of the invention, an electrical switch is coupled in series with the power supply for the motor and is actuated by the spring-loaded locking pin such that, when the hub is locked against rotation for removal of the driver disk, the interlock switch prevents inadvertent activation of the motor when the hub is locked. In a preferred embodiment of the invention, the quick disconnect hub includes a conical tapered surface, as does the driver disk, to precisely center the driver disk on the hub upon installation. In another embodiment of the invention, in place of a threaded interconnection between the driver disk and the hub, the hub includes an annular groove and the disk includes a spring-loaded plunger which snap-fits the driver disk to the hub.
These and other features, objects and advantages of the present invention will become apparent upon reading the following description thereof together with reference to the accompanying drawings.